function smoveKneeDown(world_handles)
	J0 = 1;
	J1 = 0.2;
	J2 = 2;
    speed = 0.01;
    human_reset_right(world_handles)
    youdatui = world_handles.youdatui;     youdatui.rotation   = [1 0 0 -1];
    youxiaotui = world_handles.youxiaotui; youxiaotui.rotation = [1 0 0 1];
    
    % - It is a STATE, rather than a on-going course.
    youxiaotui.rotation = [1 0 0 J2];
%     for i=J0:J1:J2
%         youxiaotui.rotation = [1 0 0 i];
%         pause(speed);
%     end
end